Application of the triple Langmuir probe to study local plasma parameters in the radiofrequency discharge that is placed in an additional applied magnetostatic field

2021 ◽  
Vol 28 (3) ◽  
pp. 033502
Author(s):  
Vladimir Kozhevnikov ◽  
Andrey Melnikov ◽  
Sergey Khartov
Keyword(s):  
Langmuir Probe ◽  
Plasma Parameters ◽  
Magnetostatic Field ◽  
Radiofrequency Discharge

Plasma parameters in positive voltage pulses of bipolar HiPIMS discharge determined by Langmuir probe with a sub-microsecond time resolution

2020 ◽  
Vol 29 (8) ◽  
pp. 085016
Author(s):  
Andrea Dagmar Pajdarová ◽  
Tomáš Kozák ◽  
Zdeněk Hubička ◽  
Martin Čada ◽  
Pavel Mareš ◽  
...  
Keyword(s):  
Time Resolution ◽  
Langmuir Probe ◽  
Plasma Parameters ◽  
Positive Voltage ◽  
Voltage Pulses

A Double Hemispherical Probe for the Advancement of In Situ Plasma Measurements

2020 ◽  
Author(s):  
Joseph Samaniego ◽  
Xu Wang
Keyword(s):  
Langmuir Probe ◽  
High Surface ◽  
Low Density ◽  
Saturation Current ◽  
Langmuir Probes ◽  
Plasma Parameters ◽  
Ambient Plasma ◽  
Surface Emission ◽  
Plasma Measurements

<p>Langmuir probes are conductors of simple geometries (spheres, disks, cylinders, etc.) inserted into a plasma. By sweeping a voltage on the probe and measuring the current collected or emitted, a current-voltage (I-V) relationship can be found and interpreted to derive the density, temperature, and potential of the ambient plasma. Over the past 50 years, Langmuir probes have been flown on spacecraft missions for in-situ measurements of the local plasma environment. However, even after decades of use, there are still challenges in the analysis and interpretation of Langmuir probe measurements due to local plasmas created around the probe as a result of plasma interactions with the probe itself and spacecraft.</p><p>The Double Hemispherical Probe (DHP) is a directional Langmuir probe made of two hemispheres that are electrically isolated from each other and swept with a voltage together to get two separate I-V curves. The DHP uses the I-V curve differences between the two hemispheres to gain information of the asymmetry of the local plasma around the probe to retrieve the true ambient plasma parameters. Specifically, the DHP is intended to improve the plasma measurements in the following scenarios: i) Low-density plasmas; ii) flowing plasmas; iii) high-surface-emission environments; and iv) dust-rich plasmas. The following discusses the current progress of the DHP development.</p><p>Low-density plasmas create large Debye sheaths around the spacecraft that may engulf the Langmuir probe attached to a boom with a finite length. The potential drop in the sheath can change the characteristics of charged particles collected by the probe, causing mischaracterization of the ambient plasma. As expected, the I-V curves of both hemispheres match in the bulk plasma. It was found that as the DHP is moved ‘deeper’ into the sheath of the spacecraft, the currents of the two hemispheres diverge. The saturation current ratio of the hemispheres of the DHP was found to have monotonic relationships with the plasma characteristics measured in the sheath. A technique was created to retrieve the ambient plasma parameters.</p><p>In space ions generally have relative velocities with respect to the spacecraft due to flowing plasmas or fast-moving spacecraft, creating an ion wake behind the probe itself. This self-wake can cause issues in interpreting the I-V curves for both ion and electron species. The ion saturation current of either hemisphere of the DHP is dependent on the ion Mach number (the ratio of the ion flow speed to the thermal speed). Electrons are generally in the thermal state. However, depending on the ratio of the probe size to the Debye length, ambipolar electric fields can be created at the wake boundaries, causing the reduction of the electron density in the downstream side of the probe and its subsequent underestimation measured by traditional single Langmuir probes. It was shown that the DHP can identify this self-wake effect and properly measure the true ambient plasma parameters.    </p><p>Future work will explore the effects of high-surface-emission environments and dust-rich plasmas on DHP measurements and to develop techniques to resolve the true ambient plasma parameters in these environments. </p>

Study of plasma parameters in a pulsed plasma accelerator using triple Langmuir probe

2018 ◽  
Vol 25 (1) ◽  
pp. 013532 ◽  
Author(s):  
S. Borthakur ◽  
N. Talukdar ◽  
N. K. Neog ◽  
T. K. Borthakur
Keyword(s):  
Langmuir Probe ◽  
Plasma Accelerator ◽  
Pulsed Plasma ◽  
Plasma Parameters

Influence of the Langmuir Probe Shaft on Measuring Plasma Parameters

2008 ◽  
Vol 48 (5-7) ◽  
pp. 534-539 ◽  
Author(s):  
O. Waldmann ◽  
G. Fussmann
Keyword(s):  
Langmuir Probe ◽  
Plasma Parameters

Langmuir probe measurements of plasma parameters in a planar magnetron with additional plasma confinement

Vacuum ◽  
1999 ◽  
Vol 55 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Petr Špatenka ◽  
Jaroslav Vlček ◽  
Josef Blažek
Keyword(s):  
Langmuir Probe ◽  
Plasma Confinement ◽  
Plasma Parameters ◽  
Planar Magnetron ◽  
Langmuir Probe Measurements ◽  
Probe Measurements

scholarly journals Comparison between mirror Langmuir probe and gas-puff imaging measurements of intermittent fluctuations in the Alcator C-Mod scrape-off layer

2020 ◽  
Vol 86 (5) ◽  
Author(s):  
R. Kube ◽  
A. Theodorsen ◽  
O. E. Garcia ◽  
D. Brunner ◽  
B. LaBombard ◽  
...  
Keyword(s):  
Time Series ◽  
Langmuir Probe ◽  
Time Series Data ◽  
Line Emission ◽  
Single Pulse ◽  
Statistical Properties ◽  
Series Data ◽  
Plasma Parameters ◽  
Order Unity ◽  
Plasma Fluctuations

Statistical properties of the scrape-off layer plasma fluctuations are studied in ohmically heated plasmas in the Alcator C-Mod tokamak. For the first time, plasma fluctuations as well as parameters that describe the fluctuations are compared across measurements from a mirror Langmuir probe (MLP) and from gas-puff imaging (GPI) that sample the same plasma discharge. This comparison is complemented by an analysis of line emission time-series data, synthesized from the MLP electron density and temperature measurements. The fluctuations observed by the MLP and GPI typically display relative fluctuation amplitudes of order unity together with positively skewed and flattened probability density functions. Such data time series are well described by an established stochastic framework that models the data as a superposition of uncorrelated, two-sided exponential pulses. The most important parameter of the process is the intermittency parameter, $\gamma = {\tau _{d}} / {\tau _{w}}$ , where ${\tau _{d}}$ denotes the duration time of a single pulse and ${\tau _{w}}$ gives the average waiting time between consecutive pulses. Here we show, using a new deconvolution method, that these parameters can be consistently estimated from different statistics of the data. We also show that the statistical properties of the data sampled by the MLP and GPI diagnostic are very similar. Finally, a synthetic GPI signal using only plasma parameters sampled by the MLP shows qualitatively different fluctuation statistics from the measured GPI signal.

scholarly journals Seismic-Lonospheric Perturbations in Lonospheric TEC and Plasma Parameters Associated with the 14 July 2019 Mw7.2 Laiwui Earthquake Detected by the GPS and CSES

2021 ◽  
Author(s):  
Yuanzheng Wen ◽  
Guangxue Wang ◽  
Dan Tao ◽  
Jiayi Zong ◽  
Zhima Zeren ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Langmuir Probe ◽  
Ionospheric Plasma ◽  
Spatial Variations ◽  
Negative Anomaly ◽  
Electron Content ◽  
Plasma Parameters ◽  
Total Electron ◽  
Ionospheric Perturbations ◽  
Geomagnetic Activities

Abstract In this study, with cross-valid analysis of total electron content (TEC) data of the global ionospheric map (GIM) from GPS and plasma parameters data recorded by China Seismo-Electromagnetic Satellite (CSES), signatures of seismic-ionospheric perturbations related to the 14 July 2019 Mw 7.2 Laiwui earthquake were detected. After distinguishing the solar and geomagnetic activities, three positive temporal anomalies were found around the epicenter 1 day, 3 days and 8 days before the earthquake (14 July 2019) along with a negative anomaly 6 days after the earthquake, which also agrees well with the TEC spatial variations in latitude-longitude-time (LLT) maps. To further confirm the anomalies, the ionospheric plasma parameters (electron, O+ and He+ densities) recorded by the Langmuir probe (LAP) and Plasma Analyzer Package (PAP) onboard CSES were analyzed by using the moving mean method (MMM), which also presented remarkable enhancements along the orbits around the epicenter on day 2, day 4 and day 7 before the earthquake. To make the investigations more convincing, the disturbed orbits were compared with their corresponding four nearest revisiting orbits, whose results indeed indicate the existence of plasma parameters anomalies associated with the Laiwui earthquake. All these results illustrated that the GPS and CSES observed unusual ionospheric perturbations are highly associated with the Mw 7.2 Laiwui earthquake, which also strongly indicates the existence of pre-seismic ionospheric anomalies over the earthquake region.

Measurement of edge plasma parameters in IR-T1 Tokamak by double Langmuir probe

2002 ◽  
Author(s):  
M. Ghoranneviss ◽  
A. Khademian ◽  
M. Masnavi ◽  
P. Khorshid ◽  
M.R. Salami
Keyword(s):  
Langmuir Probe ◽  
Edge Plasma ◽  
Plasma Parameters
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